Which Is Faster - 600hp@6200 or 600hp@7100

[kimosabi]

Which one is faster depends. Top fuel cars are max 8.250rpm or so. 8000horse? Does that make them slower than a 10.000rpm 8000hp car?

How long is a rope?

[Warp Speed]

Back to which is faster, unless you are severely limited by gearing options, as in DV's example, rpm wins EVERY TIME!
Before the gear rule, we would sometimes sacrifice power to be able to turn more rpm.

[GARY C]

Yes

I added the pictures, maybe after your post

I remember that 13 sec engine tester. Ahh the good ole days!

That was the first article I ever read, I was building an almost identical for a 79 T/A when I found the 2 part story in a shop I worked at.

[psychomotors]

Gary , I'm going to assume this was in Popular Hot Rodding?

[GARY C]

Gary , I'm going to assume this was in Popular Hot Rodding?

Yes!

[psychomotors]

Gary , I'm going to assume this was in Popular Hot Rodding?

Yes!

Thanks.

[MadBill]

...How long is a rope?

Ah; there's a formula for that: let 'A' be one end of the rope and 'B' its mid-point. The length then will be 2AB.
Q.E.D.

[Desertrunner]

In answer to the question,
If we convert the motor that spins at 7,100 back to 6,200 you get a torque number of 689 Nm for both motors. If you convert the 6,200 torque number to 7,100 you get both motors generating a torque number of 601 Nm. So no surprise there.
The speed down the drag strip is all about the amount of torque being applied to the wheels at a given speed. So based on my calc's that amount of torque will be exactly the same. As mentioned before there maybe some gains in the lower friction number but that's the limit of the difference.
Tony


PS
Hi DV I am the guy you meet in Sydney with the new intake design.

[vortecpro]

I have a question Tony:


Would you run a engine that the peak HP occurs @ 5800 RPM, and turn it 7000 RPM through the lights in a drag race situation?

[DaveMcLain]

Here's an interesting example using some data from a two barrel circle track engine which was making 486 horsepower at its peak at 6200rpm. At 7100 it was making 462 horsepower and at 5200rpm it was also making 462 horsepower. At the track the car is geared to turn about 7200rpm. I know what it would run like if it was only turning 5200rpm, it wouldn't be good. In an ultimate speed test though would the car go the fastest if it were geared to turn 5200, 6200 or 7200rpm?

[vortecpro]

RPM is wheel speed, pretty simple.

[AMXstocker1]

so more rpm is ultimately better even if the car doesn't make power there? i've seen a car pick up going from 4.88s to 4.10s in the 1/4 and that motor probably peaked around 5800-6000 10.1 390 with a 230-236@.050 hydraulic flat tappet with around .550 lift a torker and 850 holley. picked up 3 tenths with the gear change same tire and the difference in trap was 7100 with 4.88s and 6200 with 4.10s given power probably took a pretty big dive above 6000

[plovett]

Most people would say that an engine that makes hp at a higher rpm requires more gearing to run optimally. But, I would say that the same higher rpm engine also allows you to run more gearing. Think about it.

It's a win for the high rpm engine, in my opinion. Obviously, there are drawbacks to running higher rpm, but speed is not one of them.

JMO,

paulie

[plovett]

so more rpm is ultimately better even if the car doesn't make power there? i've seen a car pick up going from 4.88s to 4.10s in the 1/4 and that motor probably peaked around 5800-6000 10.1 390 with a 230-236@.050 hydraulic flat tappet with around .550 lift a torker and 850 holley. picked up 3 tenths with the gear change same tire and the difference in trap was 7100 with 4.88s and 6200 with 4.10s given power probably took a pretty big dive above 6000

You are talking about optimizing the gearing for a given combination. In your example 4.88's were too much gear for the engine. If the engine could make the same power at higher rpm, then maybe it could utilize more gear.

[user-23911]

Nobody has yet said how they'd build the 2 engines to make the quoted numbers .

As I said a few pages back, the one that makes the power at lower revs has boost.

The one that makes the same power at higher revs has a hot cam.


Boost always wins.